Marcus Folkesson

Embedded Linux Artist

2.2" TFT display on Beaglebone

2.2" TFT display on Beaglebone I recently bought a 2.2" TFT display on Ebay (come on, 7 bucks...) and was up to use it with my BeagleBone. Luckily for me there was no Linux driver for the ILI9341 controller so it's just to roll up my sleeves and get to work. Boot up the BeagleBone I haven't booted up my bone for a while and support for the board seems

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Posted by Marcus Folkesson on Sunday, August 27, 2017

High resolution timers

High resolution timers Nearly all systems has some kind of Programmable Interrupt Timer (PIT) or High Precision Event Timer (HPET) that is programmed to periodically interrupt the operating system (if not configured with CONFIG_NO_HZ). The kernel performs several tasks in these ticks such as timekeeping, calculate statistics for the currently running process, schedule a new process and so on. The interrupt occurs at regular intervals - exactly HZ times per second.

Posted by Marcus Folkesson on Thursday, July 27, 2017

Modules with parameters

Modules with parameters Everybody knows that modules can take parameters, either via /sys/modules/<module>/parameters, sysctl or via cmdline to the kernel, but how are these parameters created? Parameters without callbacks The Linux kernel provides the module_param() macro. The syntax is: 1module_param(name, type, perm) Which will simply create the module parameter and expose it as an entry in /sys/modules/<module>/parameters. Code example 1int debug_flag; 2module_param(debug_flag, bool, S_IRUSR | S_IWUSR | S_IRGRP) 3MODULE_PARM_DESC(debug_flag, "Set to 1 if debug should be enabled, 0 otherwise"); MODULE_PARM_DESC() is a short description of the parameter.

Posted by Marcus Folkesson on Tuesday, June 27, 2017